Heat pump



HEAT PUMP ,Filed Jan. 15, 1938 J Inventor:

H 6.! Gibson b flan 76 H is Attorney.

Patented Nov. 1, 1938 UNITED STATES PATENT OFFICE r HEAT PUMP a g I IalGibson, Dallas, Texl, assignor to General Electric Company, acorporation of New York Application January 1938, Serial No. 185,165

7Claims.

My invention relates to systems for conditioning the air within rooms orenclosures, and particularly to such systems which utilize reversiblerefrigerating machines to supply both heating 5 and cooling medium.

Reversed cycle refrigerating machines or heat pumps, are frequentlyemployed to supply the heating units of air conditioning systems. Heatpumps require a suitable source of heat such as 0 well water, water fromcity mains, or outdoor air. In such systems, particularly those usingcity water, it is desirable to utilize the water as economically aspossible since it is necessary to circulate considerable quantities ofwater whenever the refrigerating machine is in operation. Accordingly,it is an object of my invention to provide an air heating systemutilizing a reversed cycle refrigerating machine and having an improvedarrangement for controlling the 2 supply of fluid constituting the heatsource.

Another object of my invention is to provide an air conditioning systemutilizing a refrigerating machine for pumping heat between a fluidmedium and the air within an enclosure to be conditioned to therebyeither heat or cool the air within the enclosure, which system includesan improved arrangement for controlling the supply of fluid medium.

Furtherobjects and advantages of my invention will become apparent asthe following description proceeds, and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and forming a part of this specification.

For a better understanding of my invention, reference may be had to theaccomanying drawing, the single figure of which shows diagrammaticallyan air conditioning system embodying my invention.

an air conditioning system including a duct it! connected to receive airfrom an enclosure to be conditioned through an inlet 'II and fresh airfrom outside the enclosure through an inlet 2,

the wall of the enclosure being indicated at i3 and the outside wall ofthe building at ll. A

fan I! driven by a motor i3 is provided to circulate air through theductl0, and into the enclosure or room to 'be conditioned through an outletDust and particles of foreign matter are removed by a filter i3 arrangedat the entrance provide a heat exchange element l9 arranged- 55 withinthe duct and comprising a coil connected Referring now to the drawing, 1have shownin the refrigerant circuit of a reversible refrigeratingmachine. The refrigerating machine includes a compressor driven by amotor 2i, a heat exchanger or coil 22 which may serve either as acondenser or evaporator depending upon the direction of flow ofrefrigerant in the circuit, and a liquid receiver 23. The heat exchangeri9 is connected as the second heat exchange element in the refrigeratingcircuit, andmay be employed either as a condenser or an evaporatordepending upon the direction of flow ofrefrigerant in the circuit. Aplurality of normally closed spring biased solenoid valves 24, 25, 26and 21 are provided in order to control the direction of flow ofrefrigerant in the refrigerating circuit. These valves are arranged tooperate in series, the valves 24 and 25 being opened and the valves 26and"2'l being closed when it is desired to cool the air passing throughthe duct i0, and the valves 26 and 21 being opened and the valves 24 and25 being closed when it is desired to heat the air passing through theduct i0. A supply of fluid medium, such as well water or water from thecity mains, is circulated over the heat exchanger 22 through a suitablecasing 28, in order to supply heat thereto when the refrigeratingmachine is used to heat the air in the duct ill, and to absor heat fromthe heat exchanger when the refrigerating machine is used to cool theair in the duct l0. Water is supplied to the casing 28 through pipes 29and 30, the direction and rate of flow of -the water being controlled ina manner to be hereinafter described.

When the refrigerating machine is employed to heat the air passingthrough the duct iii, the compressed refrigerant is discharged from thecondenser through a conduit 3i. 'I'hevalves 26 and 21 being opened andthe valves 24 and 25 closed, the hot compressed refrigerant flowsthrough the coils of the heat exchanger l9 and heats the air in theduct. The refrigerant is thereby cooled and liquefied and flows outthrough a connection 32 and a check valve 33 to the liquid receiver 23.A check valve 34 is provided to preventfiow of the refrigerant through aconduit 35 by-passing the valve 33. Manual shut-off valves 36 and 31 oneither side of the receiver 23 are maintained open'whenever therefrigerating machine is in use. A normally closed solenoid operatedvalve 38 belowthe receiver 23 remains closed during the heatingoperation and the liquid refrigerant flows through a check valve 39 in aby-pass around the valve 38 and through a scale trap 40 to athermostatic valve is provided with a thermostatic element 42 adjacentthe outlet of the coil 22 on the side opposite the valve 4|. The valve4|, therefore, controls the flow oi. liquid refrigerant to the heatexchanger 22 which acts as an evaporator. Refrigerant within the coil 22is vaporized by the absorption of heat from the water circulatingthrough the casing 28 and the vaporized refrigerant returns through aconduit 43 and the open valve to the intake of the compressor.

When the refrigerating machine is operated to cool the air passingthrough the duct ID, the valves 24 and 25 are opened, and the hotcompressed refrigerant flows through the conduit 3| and valve 24 to thecoil 22 through conduit 43. The refrigerant is cooled and condensed inthe coil 22 and flows through the now open valve 35 to the liquidreceiver 23, the check valve 35 preventing the flow of refrigerantthrough the scale trap 45. The liquid refrigerant flows from receiver 23through check valve 34 and a scale trap 45 to a thermostatic expansionvalve 45 which controls the flow of refrigerant to the coil l5, thevalve 45 being provided with a thermostatic element 46 adjacent theoutlet side of the coil IS. The check valve 33 prevents the liquidrefrigerant by-passing the scale trap 44 and the thermostatic expansionvalve 45. The liquid refrigerant in the coil 15 absorbs heat from theair passing through the duct W and cools the air, the refrigerant beingthereby vaporized. The vaporized refrigerant returns to the compressor25 through open valve 25.

In order to humidity the air passing through the duct in when it isbeing heated, I provide a humidifier 41. Water is admitted to thehumidifier 41 through a pipe 48 under control of a solenoid valve 49. Inorder to heat the water supplied to the humidifier 41 I provide asuitable enclosure such as a casing 55 around a coil 5| formed in thedischarge conduit 3| of the compressor. The water flowing through thepipe 48 is therefore heated by the hot compressed gases flowing throughthe conduit 3|. Water which flows to the humidifier 41 is distributedover a screen 52 from a pan 53, any excess water which has not beenabsorbed in the air being removed from the duct |0 through a drain 54.

In order to control the operation of the refrigerating machine, Iprovide a thermostat 55, which may be utilized to maintain the desiredtemperature within the enclosure during both the heating and coolingoperations. Power for driving the motors I5 and 2| and for energizingthe control circuits of the system is supplied through lines 55 whichare connected to supply lines 51, a normally closed switch 55 beingprovided in one side of the lines 55 to deenergize the power and controlcircuits whenever the temperature of the water circulating over theexchanger 22 is reduced sufliciently to endanger freezing thereof withinthe casing 25.

When it is desired to heat the air passing through the duct III, thecontrol and power circuits are'prepared by closing manual switches 55and 55, the switch 55 preparing the thermostatic control and the switch55 starting the motor |5 to drive the fan I5. When there is a demand forheat, the thermostat 55 engages its left-hand contact to connect a coil5| of a relay 52 across the secondary of a transformer 53, the primaryof which is connected across the lines 55. The relay 52 is therebypicked up, the upper arm closing a holding circuit for the coil Bi, andthe lower arm connecting the coils of solenoid valves 25 and 21 acrosslines 55 to open the refrigerating machine.

the valves, and also energize and pick-up a switch 54 which energizes acoil 55 of a time delay switch 55. The time delay switch closes after apredetermined interval determined by a dashpot or other suitable timedelay mechanism 51 and, on closing, starts the motor 2| to drive Thetime delay mechanism is provided so that the solenoid valves 25 and 21will be opened before the compressor 25 is started. The refrigeratingmachine, therefore, operates to supply hot compressed refrigerant to thecoil |5 to heat the air passing through the duct -|5 in the mannerdescribed above. When the thermostat 55 is satisfied due to the heatingof the air of the enclosure to a predetermined temperature, it engagesits righthand contact and short circuits the coil 5| thereby causing therelay 52 to drop out and deenergize the control and motor circuitsthereby stopping the supply of hot refrigerant to the coil l5. Duringthe heating of the air in the enclosure, should there be a demand for anincrease in humidity, a humidostat 55 will close its contact to connecta coil 55 across the lines 55. Coil 55 opens the valve 45 to supplywater to the humidifler 41, the water being heated by the coil 5| duringits passage through the casing 55. When the humidostat 58 is satisfied,it opens to break the circuit of the coil 55 and stop the supply ofwater to the humidifier.

The heat supplied to the air passing through the duct I5 is pumped bythe refrigerating machine from the water passing through the casing 25,the rate of flow of water being controlled by a valve 15 in response tothe pressure within the return or suction line 43 of the compressor, apressure responsive switch 1| being employed for this purpose. Thedirection of the flow of water through the casing 25 is controlled bythree-way solenoid valves 12 and 13, and the position of these valves isdetermined by the lower arm of a switch 14. The valves 12 and 13 areprovided with actuating coils 12a and 150 respectively. The direction offlow of water through the casing 25 is maintained in counterflow to thedirection of refrigerant flowing through the coil 22, so that there is amaximum efflciency of heat exchange between the water and refrigerantduring both the heating and cooling operations. The valves 12 and13-reverse the water circuit when the refrigerant circuit is reversed.When the switch 14 is in its drop out position, which is its positionduring the heating operation, the coil 13a of the solenoid of the valve15 is connected across the lines 55' and the coil 12a of the valve 12 isnot energized. The coils 12a and 13a cannot be energized simultaneously.During the heating operation with the coil 13a energized, water flowsfrom a supply pipe 15 through the valve 12 to the pipe 25, the valve 15being connected in the pipe 25 to control the flow of watertherethrough. A manual valve 15 is provided to shut off the flow ofwater through the pipe 25 if desired. Water flows from the pipe 25through the casing 25 to the pipe and thence through the valve 15 to areturn pipe 11. The pressure control switch 1| cooperating with acontrol mechanism 15 of the valve 15 maintains a predetermined pressurewithin the evaporator coil 22. The control mechanism 15 includes areversible induction motor 15 of the shaded pole type. The motor drivesthe valve through a worm and pinion 55 and 5| respectively. Cams 52 and55 are provided to operate limit switches to determine the limitingposition of the valve 18 at either end of its movetion of rotation ofthe motor. As long as both the windings 86 and 81 are open circuited,the motor remains stationary. As soon as one of the windings 86 or 81 isshort-circuited, torque is developed and the motor rotates the valveuntil the short circuit is opened by the pressure switch or until one ofthe cams 82 and 83 operates its corresponding one of limit switches 88and 89 respectively. The pressure responsive switch 1| operates toshort-circuit the windings 86 and 81 depending upon the pressure withinthe conduit 43. When the pressure increases to a predetermined value,the switch 1| closes its upper set of contact and short-circuits coil 86causing the valve 18 to rotate in a direction to decrease the flow ofwater through the casing 28. When the pressure within the conduit 43decreases to a predetermined low value, the switch 1| closes its lowerset of contacts to short the coil 81 and cause the valve 18 to rotate ina y direction to increase the flow of water through the casing 28. Itis, therefore, evident that by selecting the desired range of limits forthe operation of the switch 1|; the pressure within the evaporator 22may be maintained within any desired range and thus limit the load onthe compressor. 'The required supply of heat to the evaporator 22 isthereby maintained with a minimum flow of water through the casing 28for whenever there is more water flowing through the casing thanrequired, the supply is limited by operation of the valve 18. Moreefiicient operation of the refrigerating machine is obtained because thetemperature of the evaporator is not permitted to become too low, andmore economical operation is obtained by not permitting the temperatureof the evaporator to become too high. Should the water in the casing 28for any reason, such as the failure of the operating coil 9| of switch14 is also energized deenergize the motor and control circuits and stopthe operation of the system';

When it is desired to cool the air within the enclosure, a manualswitch98 is closed, switch 58 being open, and the switch 68 is closed inorder to drive the motor l6. The closing of the switch 98 prepares themotor and control circuits for the cooling operation. During the coolingoperation, the relay 62 falls to its drop out position when there is ademand for cooling, since the thermostat 55 engages its right-handcontact whenever the room temperature reaches a predetermined high valueand short-circuits the coil 6!. On a demand for cooling, when the relay62 is in its drop out position, the coils of solenoid valves 24 and 25are connected across the lines 56 through the switch 98 and the bottomarm of the relay 62, and the valves 24 and 25 are thereby opened. Valves26 and 21 cannot be energized since the switch 59 is open. Ari

and the switch 14 is picked up. The upper arm of the switch 14 closes acircuit of the coil 65 and the time delay switch 66 closes after aninterval to start the motor 2| and operate the refrigerating machine tosupply liquid refrigerant to the heat exchange element l9. The lower armof invention.

the switch 14 in its pick-up position energizes the coil 12a and opensthe circuit of the coil 1311, thereby reversing the positions of thevalves 12 and 13. Water from the supply pipe 15 flows through the valve12 and through a pipe 92 to the pipe 38. A manual valve 93 is providedin the' pipe 92. to close the pipe and prevent the flow of watertherethrough when desired. The

valve 13 is in position to prevent the flow of water therethrough fromthe pipe 38 and the water flows from the pipe 38 to the casing 28 andthence through the pipe 29 and a pipe 94 to the outlet 11 through thevalve 13. In order to control the flow of water through the pipe 94, Iprovide a valve 95 operated by a pressure element 96 which is incommunication with the discharge pipe 3| of the compressor 28. The valve95 is, therefore, controlled in response to the head pressure of thecompressor, the flow of water through the casing 28 being increased on arise in head pressure and vice versa. It will be noted that the waterflowing through the casing 28 flows in the opposite direction from thatof the. refrigerant flowing through the coil 22. refrigerating machineis operating to cool the air passing through the duct l8, compressedrefrigerant is discharged through the conduit 43 and the pressureelement 1| is thereby maintained at a. relatively high pressure. Theupper contacts will then be closed and the motor 19 will operate untilthe cam 82 opens the circuit of the coil 86 thereby preventing furtherrotation of the motor and holding it in its limiting position pending asubsequent reduction of the pressure in the element 1|. The motor 19 is,therefore, not operated during the cooling operation.

During the operation of the. refrigerating machine, should the backpressure at any time be reduced to a predetermined minimum, a pressureresponsive switch 91 will operate to open its contacts and stop furtheroperation of the motor 2| until the pressure has again increased tonormal. This is the type of back pressure control commonly employed inrefrigerating machines to prevent excessive low pressures andtemperatures.

From the foregoing, it is evident that I have provided an airconditioning system utilizing a refrigerating machine as a heat pumpto'either heat or cool the air within an enclosure and-that the systemis so arranged as to provide the most eflicient use of the coolingmedium which is utilized to cool the condenser during the coolingoperation or to supply heat to the refrigerating machine during theheating operation.

While I have described a particular embodiment of my invention inconnection with an air conditioning system, other modifications will beapparent to those skilled in the art. I do not, therefore, desire myinvention to be limited to the particular construction shown anddescribed and I intend in the appended claims to cover all modificationswithin the spirit and scope of my What I claim -'as new and desire-tosecure b Letters Patent of the United States is:

1. A fluid heating system including a reversed cycle refrigeratingmachine having a compressor evaporator to supply heat to said system,and- While the means dependent upon the pressure of the vaporizedrefrigerant withdrawn from said evaporator for controlling the rate offlow of said heat supplying fluid over said evaporator to limit the loadon said compressor.

2. A system for heating the air within an enclosure including a duct, areversed cycle refrigerating machine having a compressor and anevaporator and a condenser, said compressor being arranged to supplycompressed refrigerant to said condenser and towithdraw vaporizedrefrigerantfrom said evaporator, means for circulating air through saidduct and into said enclosure, means including said condenser for heatingthe air circulated through said duct, means for circulating a fluid oversaid evaporator to supply heat to said system, and means dependent uponthe pressure of vaporized refrigerant withdrawn from said evaporator forcontrolling the rate of flow of said fluid over said evaporator to limitthe load on said compressor.

3. ,A system for conditioning the air within an enclosure including aduct, a reversed cycle refrigerating machine having a compressor and anevaporator and a condenser, said compressor being arranged to supplycompressed refrigerant to said condenser and to withdraw vaporizedrefrigerant from said evaporator, means for circulating air through saidduct and into said enclosure, means including said condenser for heatingthe air circulated through said duct, means for circulating a fluid oversaid evaporator to supply heat to said system, means dependent upon thepressure of vaporized refrigerant withdrawn from said evaporator forcontrolling the rate of flow of said fluid over said evaporator to limitthe load ,on said compressor, means for reversing the operation of saidrefrigerating machine to supply liquid refrigerant to said condenser tocool the air circulating through said duct and to supply heat to thefluid circulated over said evaporator, and means dependent upon thepressure of refrigerant discharged by said compressor for controllingthe flow of said fluid over said evaporator to limit the load on saidcompressor when the operation of said refrigerating machine is reversed.

4. A system for conditioning the air within an enclosure including aduct, a reversed cycle refrigerating machine having a compressor and anevaporator and a condenser, said compressor being arranged to supplycompressed refrigerant to said condenser and to withdraw vaporizedrefrigerant from said evaporator, means for circulating air through saidduct and into said enclosure, means including said condenser for heatingthe air circulated through said duct, means for circulating a fluid oversaid evaporator to supply heat to said system, means dependent upon thepressure of vaporized refrigerant withdrawn from said evaporator forcontrolling the rate of flow of said fluid over said evaporator to limitthe load on said compressor, means for reversing the operation of saidrefrigerating machine to supply liquid refrigerant to said condenser tocool the air circulating through said duct and to supply heat to thefluid circulated over said evaporator, means for reversing the directionof flow of fluid over said evaporator, and means dependent upon thepressure of refrigerant dischargedby said compressor for controlling therate of flow of said fluid in said reversed direction.

5. A system for heating the air within an enclosure including a duct, areversed cycle refrigerating machine having a compressor and anevaporator and a condenser, said compressor being arranged to supplycompressed refrigerant to said condenser and to withdraw vaporizedrefrig- -erant from said evaporator, means for circulating air throughsaid duct and into said enclosure, means including said condenser forheating the air circulated through said duct, means dependent upon thetemperature of the air within said enclosure for controlling theoperation of said refrigerating machine, means for circulating a fluidover said evaporator to supply heat to said system, and means dependentupon the pressure of vaporized refrigerant withdrawn from saidevaporator for controlling the rate of flow of said fluid over saidevaporator to limit the load on said compressor.

6. A system for heating the air within an enclosure including a duct, areversed cycle refrigerating machine having a compressor and anevaporator and a condenser, said compressor being arranged to supplycompressed refrigerant to said condenser and to withdrawvaporiud'refrigerant from said evaporator, means for circulating airthrough said duct and into said enclosure, means including saidcondenser for heating the air circulated through said duct, meansarranged within said duct for supplying moisture to the air circulatingtherethrough for increasing the .relative humidity of the air withinsaid enclosure, means for supplying water for said humldifying means,means utilizing a portion of the heat of compression of the refrigerantdischarged from said compressor for heating the water supplied to saidhumldifying means, means dependent upon the relative humidity of the airwithin said enclosure for controlling the flow of water to saidhumidifying means, means for circulating a fluid over said evaporator tosupply heat to said system, and means dependent upon the pressure ofvaporized refrigerant withdrawn from said evaporator for controlling therate of flow of said fluid over said evaporator to limit the load onsaid compressor.

7. A system for heating the air within an enclosure including a duct, areversed cycle refrigerating machine having a compressor and anevaporator and a condenser, said compressor being arranged to supplycompressed refrigerant to said condenser and to withdraw vaporizedrefrigerant from said evaporator, means for circulating air through saidduct and into said enclosure, means including said condenser for heatingthe air circulated through said duct, means for circulating a fluid oversaid evaporator to supply heat to said system, means dependent upon thepressure of vaporized refrigerant withdrawn from said evaporator forcontrolling the rate of flow of said fluid over said evaporator to limitthe load on said compressor, said flow controlling means being arrangedto vary the rate of flow of fluid over said evaporator substantially inproportion to the change of pressure of said vaporized refrigerant.

HAL GIBSON.

